diff --git a/CHANGES b/CHANGES
index b5b5d1ee8..e8d72d06d 100644
--- a/CHANGES
+++ b/CHANGES
@@ -30,6 +30,9 @@ Bugs fixed
 
 * #932: autodoc: Do not crash if ``__doc__`` is not a string.
 
+* #933: Do not crash if an ``:option:`` value is malformed (contains spaces
+  but no option name).
+
 Documentation
 -------------
 
diff --git a/sphinx/domains/std.py b/sphinx/domains/std.py
index ae67bf0e6..50e519fab 100644
--- a/sphinx/domains/std.py
+++ b/sphinx/domains/std.py
@@ -190,17 +190,26 @@ class Program(Directive):
 class OptionXRefRole(XRefRole):
     innernodeclass = addnodes.literal_emphasis
 
+    def _split(self, text, refnode, env):
+        try:
+            program, target = re.split(' (?=-|--|/)', text, 1)
+        except ValueError:
+            env.warn_node('Malformed :option: %r, does not contain option '
+                          'marker - or -- or /' % text, refnode)
+            return None, text
+        else:
+            program = ws_re.sub('-', program)
+            return program, target
+
     def process_link(self, env, refnode, has_explicit_title, title, target):
         program = env.temp_data.get('std:program')
         if not has_explicit_title:
             if ' ' in title and not (title.startswith('/') or
                                      title.startswith('-')):
-                program, target = re.split(' (?=-|--|/)', title, 1)
-                program = ws_re.sub('-', program)
+                program, target = self._split(title, refnode, env)
                 target = target.strip()
         elif ' ' in target:
-            program, target = re.split(' (?=-|--|/)', target, 1)
-            program = ws_re.sub('-', program)
+            program, target = self._split(target, refnode, env)
         refnode['refprogram'] = program
         return title, target
 
diff --git a/tests/root/markup.txt b/tests/root/markup.txt
index 1fb20cf09..39a8ebc07 100644
--- a/tests/root/markup.txt
+++ b/tests/root/markup.txt
@@ -139,6 +139,7 @@ Adding \n to test unescaping.
 * :doc:`subdir/includes`
 * ``:download:`` is tested in includes.txt
 * :option:`Python -c option <python -c>`
+* This used to crash: :option:`Python c option`
 
 Test :abbr:`abbr (abbreviation)` and another :abbr:`abbr (abbreviation)`.
 
diff --git a/tests/test_build_html.py b/tests/test_build_html.py
index d5b59e42f..bd8c0730a 100644
--- a/tests/test_build_html.py
+++ b/tests/test_build_html.py
@@ -42,6 +42,8 @@ http://www.python.org/logo.png
 reading included file u'.*?wrongenc.inc' seems to be wrong, try giving an \
 :encoding: option\\n?
 %(root)s/includes.txt:4: WARNING: download file not readable: .*?nonexisting.png
+%(root)s/markup.txt:142: WARNING: Malformed :option: u'Python c option', does \
+not contain option marker - or -- or /
 %(root)s/objects.txt:\\d*: WARNING: using old C markup; please migrate to \
 new-style markup \(e.g. c:function instead of cfunction\), see \
 http://sphinx-doc.org/domains.html